1. Field of The Invention
The present invention relates to a gas-blast circuit-breaker and more particularly to a high-voltage gas-blast circuit-breaker, each of whose poles includes several groups of arc-extinguishing chambers, these groups being supported at the same horizontal level above the ground by a support formed by insulating columns or pillars fixed on a base.
2. Background of the Invention
In known devices, each group generally includes two or four aligned arc-extinguishing chambers and a control box disposed between the chambers. The gas in the control box communicates with the chambers and the control mechanism of the control box is connected to these chambers by control rods for opening and closing the circuit-breaker. The lower portion of the control box includes a plate to which is fixed the top of a tubular column whose base is fixed on a base which is perpendicular to the plate. The column is formed by a stack of insulators and contains the compressed gas which comes from a source situated at the level of the base so as to convey the gas towards the box and the arc-extinguishing chambers. The column also contains means for transmitting the force to operate the circuit breaker control rods, these means comprising axial links whose tops are articulated with the control rods. A set of horizontal links is disposed at the level of the base to connect the bases of the vertical links to the mechanism of an actuator, the vertical links being situated in the successive columns of the various groups.
Pillars which have only a supporting function and which therefore contain neither gas nor operating means can also be fixed between the base and the plates of the various groups so as to increase the stability of the device.
Circuit-breakers of this type have drawbacks.
Indeed, when the rated voltage of the circuit-breaker increases, the insulating support is longer and must have greater resistance to bending. For that purpose, keeping the dimensions of the various insulators of each column identical, these insulators can be made of materials which have different mechanical strength, so that the insulators situated at the base of the column will have improved mechanical strength. Also, still keeping the dimensions of the insulators of each column identical, insulating tie rods can be added to the insulators situated at the base of the column, the tie rods increasing the mechanical strength of the assembly. Also, insulators with a larger diameter or thicker insulators can be provided at the base of the column. But all cases lead to increasing the number of types of elementary insulators.
Further, a very long insulating support (several meters in length) which has a small diameter and whose end supports heavy arc-extinguishing chambers has less resistance to earthquakes.
Lastly, circuit-breakers of this type have the disadvantage of requiring a very long length of links.
When the circuit-breaker includes several modules which include supports several meters apart and supporting arc-extinguishing chambers in series, the arc-extinguishing units must have synchronized movements on closing and more especially on opening. This synchronization is difficult to obtain, since any play must be compensated and expansion and shrinkage of the connection links due to variations in temperature must be taken into account.
The present invention aims to mitigate these drawbacks and to control more simply and more accurately the opening and closing of gas-blast circuit-breakers which have several groups of arc-extinguishing chambers supported by insulating columns and pillars.